On A Product Page, Does The Product Name Have An H1 Tag?

Yes, the Product Name is the H1 Tag

What Is Schema/Jason HTML Tag?

Schema.org or Microdata/Rich Tagging is an advanced method of tagging elements throughout your store that are important for search engines. Zoey automatically tags your Categories, Products and Blog Posts with the most relevant information. You can read about what we do here: https://support.zoey.com/v1.0/docs/microdata-structured-data-schemaorg

How To Ask Customers For A Review And How To Reward Them?

Zoey does not have a mechanism for this but you can use apps such as MailChimp, YotPo or TrustPilot to do this.

Is The Search Engine Preview Description The Meta Description?

Yes, that is correct. The Product Description or Category Overview becomes the Search Engine Preview Description. However, you can edit this and enter a different Search Engine Description.

What Is The Role Of The Product Overview Field?

This information is valuable for SEO. It get's tagged as the item description in schema.org microdata. The Description is also important and should be different from the Overview.

What Fields Should We Improve For SEO?

You will need SEO friendly names/product titles, URL's, meta description field, photo names and alt tags.
Depending on your business needs and what you're selling you may need to add the ItemCondition tag: https://support.zoey.com/v1.0/docs/microdata-structured-data-schemaorg#section-item-condition-tag But I would ask that you consult an SEO expert to see if there is anything more you need to do.

Do I Continue To Use Keywords?

Google started ignoring Meta-Keywords. We recommend making any long-tail keywords visible and/or embedded into your product descriptions.